This invention relates to a conveyor apparatus and, more particularly, to an accumulation conveyor adapted to absorb an irregularity of working times in a number of working steps provided along predetermined rails by moving a truck along the rails and stopping the truck at arbitrary positions.
There are heretofore as conventional accumulation conveyors an accumulating system, as disclosed in Japanese Patent Publication No. 8604/84 official gazette, for accumulating a truck by stopping the truck by a stopper, disengaging and stopping the contact or engagement with a conveying strip member such as a belt or a chain in case of stopping the truck in contact with the preceding truck, and another accumulating system, as disclosed in Japanese Utility Model Application Laid-open No. 95,776/75 official gazette, for accumulating a truck without disengaging the contact or engagement with the conveying strip member.
In the former system for accumulating the truck by disengaging and stopping the contact or engagement with the strip member, it is necessary to separately provide a mechanism for disengaging the contact with the belt of the strip member or the engagement with the chain. Thus, the structure of the system as a conveyor apparatus becomes complicated, the truck at the accumulating time not being engaged but being held in a freely movable state. Therefore, it is necessary to provide a position restricting unit for preventing the truck from freely moving, and it has drawbacks such as an expensive cost of the entire conveyor apparatus.
In the latter system for accumulating the truck without disengaging the contact or engagement with the strip member, a line pressure as a reaction of a new engaging force such as slipping frictional force between the belt and the roller or slipping frictional force in a frictional joint with the chain wheel by the belt at the accumulating time generally increases so as to resist against the new engaging force, and it is necessary to increase the strength of the stopper and the strength of the conveying strip member such as the belt or the chain so as to resist against the reaction. Thus, if the line pressure is reduced, the engaging force should be decreased, and the engaging force of the stopper is accordingly released. Consequently, when the truck is again started, it has the drawback that slippage occurs and the truck cannot readily start.